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Aditya Prakash avatar image
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Aditya Prakash asked Phil BoBo edited

Has anyone tried modelling a Multi agent system on a Grid based layout.

Hi, I'm evaluating whether FlexSim is a suitable tool to simulate multi agent AGV based warehouse,(Somewhat like KIva). Few fundamental doubts I have are (Pic: A small 6 square grid.)

1. Whether we can build a grid based layout for agvs. (control point being at the center of each square)

2. Reserve/Release grid points. (control points). Crudely it works by reserving a certain set of grid points for an AGV and those points are released once AGV has passed those points.

3. Override the default navigation (probably A*) for agvs and build a custom navigator.

4. Can agv differential steering (Turning at same point, control point) be modeled ? Turning speed as a input parameter.

FlexSim 16.1.0
agvcustom navigationmulti-agent
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Joerg Vogel avatar image Joerg Vogel commented ·

What is your intention? - A model that computes results or an accurate visual animation. Maybe you can build first a model that doesn't looks realistic but computes results and then control the behaviour of a nice looking 3D model. For example you have a plant that has to be maintained at breakdown of machines. The breakdowns happen randomly. If the plant has got 100 machines and 4 service operators you can build a grid of 100 machines and activate the breakdown by MTBF/MTTR for each of them. The operators walk to the machines and work on them. Another approach is just to create repair task randomly and let 4 processors, which are representing the service operators, do the work on flowitems. Those flowitems are the repair tasks. Which model is easier to build?

Edit: Back to your question - in standard flexsim without the AGV module you can build a network grid. At such grid you can close and open the paths edges to and from network nodes by code. And then you can tell the navigator to optimize the network for travel operation again. That is also just a command. Another approach is setting the capacity at the network nodes or to use a traffic control objects.

If there exists a similar approach in the AGV module I can't tell you. I didn't tested it so far.

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Joerg Vogel avatar image
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Joerg Vogel answered Phil BoBo edited

1. and 2.: You can build a network and control the paths accessibility to and from of the network nodes.

3. In Flexsim you find a navigator object in the model and library tree. You can change the behaviour of objects in flexsim. But I haven't adjusted a navigator. There are other methods to control the navigation, too.

4. The AGV can turn at network nodes. That is standard. It is much more complicated to let an AGV drive backward.

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Phil BoBo avatar image Phil BoBo ♦♦ commented ·

The 18.1 beta is available with new features on the A* Navigator for traveling only at right angles, rotating in place, collision detection, and routing based on travel time.

With these features, you can use the A* Navigator to simulate multi-agent grid systems.

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